Today there are different support structure systems for wind-driven power generators depending on the type of material used for manufacture, such as wood, steel or concrete.
Wood support structures have a height limitation of about 20 m.
The most commonly used generator support towers are metal towers with either a lattice structure or a hollow frustoconical or cylindrical shape. Such towers has a series of problems such as the need for constant maintenance with treatments protecting them from rust and the short operative duration thereof due to material wear caused by fatigue (as a result of the constant tension and compression cycles caused by wind force that the towers must withstand).
Furthermore, they have the added problem that they are only usable both technically and economically for heights less than 100 m due to the high cost involved in forming sections greater than 4.5 meters in diameter at the base, because they could not be transported by road since they would not pass under the number of bridges from the factory to the wind farm.
Therefore, the range of use of such metal structures ranges from 20 m to 100 m.
Today there are different designs of support structures for wind-driven power generators made of reinforced concrete, however none of them can compete with the aforementioned metal structures in terms of pricing and ease of assembly. Such structures have the drawback of incorporating several horizontal joints between the panels forming it, requiring very expensive molds for manufacture and complex attachments of all the panels to one another based on on-site tensioning cables.
Due to the high cost of concrete support structures, they are used for heights that cannot be achieved at a reasonable or competitive cost using metal structures, i.e., 100 m and higher.
The concrete support structure for wind-driven power generators object of this invention has a series of improvements over the existing structures which allow competing with and economically improving the solution of metal structures in the range of heights from 20 to 100 m. Likewise, by means of incorporating a simple transition part it allows obtaining greater heights.
The applicant is aware of the existence of other support structures such as the case of the patent with publication number EP1474579 which discloses a structure with several segments in height, all the horizontal joints generated having to be resolved, a subsequent post-tensioning being performed on-site by attaching all the panels with cables along the entire height thereof and always outside the concrete section, the panels being of a different geometry, whereby it is necessary to manufacture several molds.
U.S. Pat. No. 2,326,010 discloses a structure that is virtually identical to the preceding structure also formed by at least two segments in height with a decreasing section, whereby it needs more than one mold to precast the panels.
Patent number US2009307998 discloses an original support structure solution formed by a ring-shaped foundation associated with two concrete segments. The peculiar feature of this structure is that it has virtually the same width as the foundation where it rests, whereby the amount of concrete and steel of the structure increases considerably, with the subsequent additional cost.
The German company ENERCON markets and manufactures a structure formed by a number of concrete rings which are post-tensioned vertically on-site, attaching several ring segments at a time with cables. This solution greatly slows down assembly due to the large amount of horizontal attachments that must be resolved.
Patent number EP2420639 discloses a solution in which all the concrete elements together with the transition part are post-tensioned continuously on-site, anchoring the cables to the foundation. The post-tensioning cables are arranged outside the concrete section. This patent details the transition part, but does not define how the concrete segment is formed. The same author discloses a variant in patent number EP2402529, disclosing a corrugated concrete section that is very hard to produce.
The present invention discloses a frustoconical- or truncated pyramid-shaped support structure for wind-driven power generators which is formed by several precast concrete panels having identical dimensions, which has no horizontal joints between panels since they have the total height of said support structure. The panels are designed such that the vertical joints have a larger opening in the upper portion than in the lower portion to enable obtaining different section widths in the upper portion of this structure.
The improvements of the present invention over the existing concrete structures are:                The absence of horizontal joints with the subsequent assembly time and cost savings.        Different section widths can be obtained in the upper portion to enable adjustment to different measurements of turbines from different manufacturers.        All the panels have the same dimensions, whereby saving in investing in molds. This improvement along with the foregoing improvement allows using a single mold for all kinds of heights and widths.        On-site post-tensioning along the entire height for anchoring to the foundation is not necessary, which reduces assembly times and costs.        Post-tensioning cables are in no case arranged outside the concrete section which drastically reduces maintenance operations with respect to solutions that do contemplate said outer cables.        